When the Syria donors' conference begins on Friday in London, all eyes will turn to Moaz al-Khatib, the new leader of Syria's opposition. A religious moderate, with impeccable revolutionary credentials, and a geologist as well, the west will be looking to see whether Khatib is a man they can do business with.

Khatib was elected on Sunday in Doha as the head of Syria's new opposition coalition, emerging from negotiations many had predicted were doomed to failure.

He now has the unenviable task of trying to unite the country's feuding anti-Assad opposition at a time when the west is reluctant to give military aid to the rebels, jihadi groups are increasingly prevalent, and the war on the ground is a bloody and murderous stalemate.

Khatib's official title is president of the Syrian National Coalition for Opposition and Revolutionary Forces. His key challenge is to turn this unwieldy new group into a force that enjoys credibility inside Syria and with the west, and which could eventually turn into a government-in-waiting.

The US and the Arab League lost patience with the coalition's predecessor, the Syrian National Council (SNC), which they viewed as ineffective, woefully out of touch and unrepresentative.

Khatib is the former imam of the Ummayyad mosque in central Damascus. He fled Syria just a few months ago, in July, after several periods of imprisonment. This, and the fact that he has lived in Syria until very recently, gives him a legitimacy that other members of the SNC, many of them long-term exiles, lacked.

Khatib originally studied geophysics. He spent six years working as an engineer. He is also a member of the Syrian Geological Society and the Syrian Society for Psychological Science, and was president of the Islamic Society of Urbanisation. His status as the former imam makes him a key figure in Syria's religious establishment.

The Syrian journalist and writer Rana Kabbani, who first met Khatib 20 years ago, says: "Over the years, we have had a very intense political conversation about what needed to be done in Syria, long discussions about what was wrong with the society and what could be done about it. He was my window into Syria at a time when I couldn't physically go there."

Kabbani added: "He comes from an area in the old city of Damascus, a part of the city that was noted for its advocacy against French colonialists, producing freedom fighters. It was a traditional Damascene Muslim scene, a devout Sunni area with a long history of resistance.

"He cared very deeply about the victims of the 1982 massacre [in the Syrian city of Hama]. He was always seeking for ways to house or educate those [survivors] that the state wanted killed or banished."

But it is Khatib's reputation as a moderate that is his most important attribute, at a time when extreme Islamist groups funded by outside powers are trying to hijack Syria's revolution. Since the uprising began, 20 months ago, Assad has played the sectarian card: telling his own Shia Alawite sect that their fortunes are inextricably bound up with the regime's survival. Without him, Assad has suggested, Alawites face the prospect of being massacred; many, though not all, Alawites believe the president.

In a speech in September, Khatib set out his own inclusive vision of a tolerant Syria in which the country's various confessions and ethnicities – Christian, Alawite and Kurd among them – would be respected.

The Christians had added a "distinctly civilised touch", he said, while Syrians also "felt the pains of the great Kurdish people". He reportedly added: "It is paramount to appreciate the characteristics of the Syrian people: Syrians are tolerant, devout and open to everyone. By nature, they reject extremism and injustice."

According to Khatib, the uprising against Assad began last year when the "arrogant" regime used brutal force to suppress anti-government demonstrators calling for peaceful change. This is the dominant view among opposition Syrians. "Syrians were compelled to take up arms in order to defend their religion, families and properties," he said. "The Syrian revolution is not a violent one. Syrian revolutionaries are peaceful."

Khatib was also outspoken about the "media smearing" of the Syrian rebel movement, both by the Syrian government and by some in the west. It was inaccurate to portray the opposition as a "hotbed of Islamic extremism, terrorism and fundamentalism", he argued.

Khatib also said he was not averse to negotiating with Assad. He added that political dialogue didn't mean "surrendering to the regime's cruelty" but was the pragmatic "lesser of two evils".

Julien Barnes-Dacey, a senior policy fellow on the Middle East at the European Council on Foreign Relations, said Khatib now had a difficult job ahead of him. "His biggest challenge is to unify the different Syrian groups under his leadership. The divisions haven't gone away. They've been swept under the carpet," he said, adding: "Khatib has come out quite recently. That gives him credibility. He also isn't seen as someone who has political ambitions of his own; he is keen to serve Syria."

According to Barnes-Dacey, Khatib's two new vice-presidents were also well-regarded figures: Riad Seif, a longtime activist, led the successful US-backed initiative to start a new Syrian opposition coalition; Suhair Atassi is a prominent female activist who established an important opposition debating salon after Bashar al-Assad succeeded his father, amid hopes he might turn into a reformist.

Khatib makes his official debut as Syria's opposition leader at an Arab League-EU conference in Cairo this week. The conference is expected to consider offering the new organisation the vacant membership position left when Syria was suspended as a member state. The effect of that would be to recognise Khatib and the new body as a legitimate representative of all Syrians.

• This article was amended on 14 November 2012. The original said Moaz al-Khatib spoke no English. That is not the case.

Follow how the day unfolded as Israel responded to mortar fire on the Golan Heights and the Syrian opposition looked for support and recognition from the international community after the formation of a new coalition